1. Technical Field
The disclosure relates to cavity filters, and more particularly relates to a resonator of a cavity filter.
2. Description of Related Art
Cavity filters are popularly applied in mobile communications. FIG. 2 is a cross-sectional view of a commonly used cavity filter 100. The cavity filter 100 comprises a cavity body 110 defining an opening in a top portion thereof and comprising a plurality of bases 1101 on the bottom portion thereof, a plurality of resonators 10 attached to the bases 1011 by screws 140, and a lid 120 to cover the opening of the cavity body 110. Each resonator 10 defines a cavity 101 in communication with the cavity body 110, and a bottom 102 secured on one of the bases 1101 by one of the screws 140. The lid 120 defines a plurality of screw holes 121 each matched with a tuning screw 130 and opposite to the cavity 101 of one of the resonators 10. The tuning screws 130 are used to adjust a resonating frequency of the cavity filter 100.
However, when adjusting the frequency of the cavity filter 100, metal shavings may be produced by the tuning screw 130, which are prone to adhere on the bottoms 102 and the heads of the screws 140, because the tuning screws 130 and the lid 120 are both made of metal materials. When the cavity filter 100 is carried from one place to another place, the metal shavings may scatter onto some sensitivity electric field areas of the cavity body 110, which results in intermodulation distortion (IMD) of the cavity filter 100.
Therefore, a need exists in the industry to overcome the described limitations.